The invention relates to a pneumatic mail station for the delivery, reception and transit of pneumatic dispatch cases with two pneumatic tube sections placed at mutually opposite limiting walls of the pneumatic mail station for coupling with an incoming forwarding tube path and an outgoing forwarding tube path as well as with an insertion or inward transfer opening for the introduction of pneumatic dispatch cases which are to be sent and an unloading or outward transfer opening for the discharge of received pneumatic dispatch cases in the same limiting surfaces and with a reception tube chamber shiftable into alignment with the pneumatic tube section associated with the incoming forwarding tube path for the reception of pneumatic dispatch cases, there being allocated to said reception tube chamber a closure device functioning at one end of the chamber in the manner of creating an air pillow decelerating the pneumatic dispatch case and an air conduit which, in the reception position of the reception tube chamber, pneumatically connects the incoming pneumatic tube section with the outgoing forwarding pneumatic tube section.
Given such a pneumatic mail station--known from the Austrian Pat. No. 353,172, FIG. 1 as well as page 4, line 33 through page 5, line 12--the closure device is designed as an electromagnetically or, respectively, motor-driven slide. The slide comprises a movable plate which is guided in a slide housing. For this purpose, the slide housing is rigidly connected to the tube chamber and is displaced in common with said tube chamber. The actual drive of the tube chamber ensues via a cog wheel mechanism which engages in the central area of the tube chamber.
Given vertical disposition of the tube chamber--the usual standard position of pneumatic mail stations--the slide is situated in the lower portion of the station. The pneumatic tube sections for the incoming and the outgoing forwarding tube paths have holes near the upper and lower boundaries of the station housing which discharge into the air conduit. A clack valve is situated in the central portion of the air conduit, said clack valve being opened for the air streaming from the top toward the bottom but being closed for the opposite air flow direction. Upon arrival of a pneumatic dispatch case from the upper transmission tube path, the slide is run into the clear cross-section of the tube chamber so that the stream of conveying air is interrupted at the tube chamber. The stream of conveying air proceeds through the holes in the pneumatic tube sections and the air conduit, so that an effective pneumatic drive is available for the incoming traveling tube until the pneumatic dispatch case enters the area of the air holes of the incoming pneumatic tube section. The deceleration path in which the pneumatic dispatch case creates an air pillow in front of it which decelerates it extends from this area to the level of the slide.
Pneumatic dispatch cases arriving from below first traverse the area of the open slide, actuate a contact after the traversal and thus redirect the direction of the conveying air stream on the one hand and, on the other hand, actuate the slide drive so that the tube chamber is closed off at the lower portion thereof. Subsequently, the same operational sequence occurs as in the arrival of a pneumatic dispatch case entering the pneumatic mail station from the top.
In the known pneumatic mail station, thus, the same reception operation is provided given the arrival of pneumatic dispatch cases arriving in the pneumatic mail station both from the top and from below, the pneumatic dispatch case moving from top toward bottom in the final phase of said reception operation. This is to be viewed as being disadvantageous insofar as there is an increasing desire in the planning of contemporary pneumatic mail systems to have the pneumatic dispatch cases enter the pneumatic mail station from below, because this makes it easier to conceal or, respectively, cover the pneumatic mail tubes by means of covers, office furniture or counters. A further disadvantage is to be seen in that the pneumatic deceleration is imperfect insofar as lightweight pneumatic dispatch cases are better and more effectively decelerated than heavy pneumatic dispatch cases; given the same air velocity in tube lines proceeding down from the top, heavy pneumatic dispatch cases exhibit higher conveying speeds than lightweight pneumatic dispatch cases. In order to also be able to effectively decelerate heavy and, thus, faster pneumatic dispatch cases, an air conduit is provided for the known pneumatic mail station given high conveying speeds of heavy pneumatic dispatch cases, said air conduit emerging from the pneumatic mail station and, in an area lying correspondingly far above the pneumatic mail station, discharging into the forwarding tube entering the pneumatic mail station from the top.